1. Field of the Invention
The present invention relates to a manufacturing method for a frame body suitable for use in the manufacture of specific parts for such as turbine-operated apparatuses and the like.
Priority is claimed on Japanese Patent Application No. 2002-203981, the content of which is incorporated herein by reference.
2. Description of Related Art
Conventionally, in gas turbines for electrical generators and the like, a structure is known in which, in order to increase the jet velocity of the combustible gas to the turbine blades, a rectangular frame body is provided on the outlet of the heat chamber through which the combustion gas flows, that is, the open part on the turbine side, and the cross-sectional area of the flow path of the combustion gas is narrowed by this frame body. Generally, the frame body is structured such that the thickness in the direction along the open surface of this frame body differs at each of the opposing edges that impart this rectangular shape. Generally, the followings are known as a manufacturing method for this frame body.
First, among the edges that impart the rectangular shape to the frame body that is to be formed, a square bar is curve molded so as to form a rectangular shape. This square bar provides a cross-sectional dimension that is equal to the thickest width in the direction along the open surface of this frame body. At this time, both end surfaces of the square bar are abutted, these end surfaces are subsequently joined by flash butt welding, and a rectangular member is formed. In addition, cutting processes are applied to predetermined edges among the edges of this rectangular member, and the edges are formed to a predetermined thickness in the direction along the open surface. Thereby, a frame body is formed in which the thickness differs at each of the opposing edges that impart the rectangular shape. In addition, methods in which a blanking process and a cutting process are applied to form a frame body are generally well-known.
However, according to the conventional manufacturing method for a frame body, first, in the case in which the frame body is formed by using a square bar, it is necessary that the cross-sectional area of this square bar be completely uniform in the longitudinal direction, and thus after the rectangular member is formed by deforming, cutting processes must be applied to the edges that are thin. Thus, there is the problem in that a large amount of waste material is produced. Furthermore, the proportion of the manufacturing time for the frame body occupied by these cutting process time is high and thus the manufacturing time for the frame body required, and coupled with the problem of the waste, there is the problem in that the frame bodies become expensive. Next, in the case in which blanking processes and cutting processes are applied to a plate to form the frame body, material positioned on the plate at the opening of the frame body and the outside of the frame body becomes unnecessary, and thus there is the problem in that very large amount of waste material is produced. Furthermore, as described above, there are the problems that a processing time is protracted and the frame body becomes expensive.